This invention relates to a router device for use in forwarding a communication between networks.
A router device connects a plurality of networks and further performs to forwarding a packet sent between the connected networks. In addition, the router device performs a traffic control for processing preferentially a specified packet in order to assure a communication quality of connection between the terminals to be communicated.
There is a certain system in which this traffic control is carried out in accordance with the management information registered in a router device by a managing person for the network. In this system, for example, as to the terminal device for performing a communication requiring a real-time characteristic, managing information for instructing a preferential processing for a packet required by the terminal device is registered in advance in the router device. However, the managing person must register managing information having the same contents in respect to all the router devices where the packet of the connection may pass in the case that a certain connection is to be registered.
In turn, it has been promoted to make a standardization for a protocol (a resource reservation protocol) capable of specifying a traffic control (assignment for a communication band) from a terminal device of a user in a network to a router device. In the system to which this protocol is applied, all the terminals in the system are provided with a program capable of performing a communication of the protocol. When a communication is started, the transmission terminal specifies a communication band width by the communication of the resource reservation protocol to a terminal of a communicating party and routers forwarding the communication. The router device may perform a traffic control in such a way that it may fulfill the specified communication band width or the like. A detailed information about the aforesaid protocol is described in "RSVP: A New Resource Reservation Protocol" L. Zhang, S. Deering, D. Estrin, S. Shenker & D. Zappala, IEEE Network 1993.9.
In the system in which a managing person registers a managing information indicating the content of the traffic control, it is necessary to perform a registration of the same content in respect to all the router devices through which a packet may pass for every connection. In the case that there are many router devices performing a forwarding, this registration may become a substantial burden for a managing person.
Adopting the reservation protocol eliminates the need for setting the information indicating the contents of traffic control to the router in the communication path because the information will be transferred by the protocol, thereby lightening the burden of the managing person. However this technique causes new problems as follows.
In a system in which a user can specify the content of traffic control by the resource reservation protocol, it is necessary to install the program capable of performing a communication of the resource reservation protocol in all the terminals, so that a high burden may be applied to the managing person when the system is constructed.
In addition, in this system, since all the users can specify the communication band width of their own connections respectively, there is a possibility that a communication band or a processing capability of a router device is occupied by a certain connection and an opening of other connections or communication quality can not be assured.